This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our experiments aim to evaluate the effect of ICG-PDT on mouse window chamber vasculature (an animal model which simulates PWS vasculature). Specifically, we are interested in determining the level of vascular shutdown achieved with ICG-PDT. Mice will receive ICG followed by laser irradiation. ICG will be injected retroorbitally allowing the ICG to diffuse into the bloodstream. Following a 1-minute delay, the epidermal side of the skin-fold will be irradiated with a GentleLASE 755 nm alexandrite laser;pulse duration and spot size will be 3 ms and 10 mm respectively. Mice will then be exposed to radiant exposures of 30, 40 or 50 J/cm2.